1. Technical Field
Improved organic anti-reflective coating polymers of the general formula I are provided as a top layer on a photoresist layer. The polymers are used as an ultra-fine pattern formation process of the photoresist in a photolithography technique using an ArF light source with a wavelength of 193 nm or a VUV light source with a wavelength of 157 nm. The disclosed organic anti-reflective coating polymers are capable of protecting photoresist patterns from amines in the atmosphere thereby minimizing a post exposure delay effect after exposure to light and, at the same time, enhancing notching status. As a result, a pattern distortion caused by diffused reflection is minimized and the reflection rate is reduced thereby minimizing a swing effect. Preparation methods and an organic anti-reflective coating composition comprising the same are also disclosed.

wherein m is an integer ranging from 5 to 5000.
2. Description of the Related Art
In semiconductor production processes, an ultra-fine pattern formation process (hereinafter abbreviated as “patterning method”) necessarily involves: standing waves caused by variations of optical property of a bottom film layer in the photoresist film and/or thickness of photosensitive film; reflective notching status; and variation of critical dimension (hereinafter referred to as CD) of patterns of the photoresist induced by diffracted light and reflected light from the bottom film layer.
Accordingly, it has been proposed that an intermediate film, a so-called anti-reflective coating, be employed which is able to prevent the light reflection in the bottom film layer prepared by introducing a material having a higher light absorption ability in the bandwidth of wavelength for the exposure light source and located between the bottom film layer and the photoresist. Especially, when exposed to UV light from the light source, a photoresist thin film is transmitted by the UV light, thus allowing the light absorbed in bottom portion of the thin film to be scattered and/or reflected. Such an anti-reflective coating can absorb the scattered and/or reflected light and, thereby, directly affecting the processing of the photoresist.
However, as the patterns are becoming ultra-fine along with the reduction of semiconductor devices to less than 90 nm, it is difficult to completely prevent pattern alteration or distortion generated due to diffused reflection using only the above anti-reflective coating. That is, a bottom anti-reflective coating (hereinafter referred to as BARC) has been introduced between the bottom film layer and the photoresist. Therefore, it requires an improved anti-reflective coating material to be applied on top portion of the photoresist or a method for forming the pattern due to solve the above problem, which can greatly reduce and/or minimize the pattern distortion caused by the diffused reflection.
In processes for forming ultra fine patterns using a light source with a wavelength of 157 nm, compounds containing fluorine as a photosensitive agent are predominately used. Such a fluorine based photosensitive compound has a problem in that it is contaminated by amine compounds in the atmosphere, since carbon-fluorine bond in the photosensitive compound may form a strong hydrogen bond with a nitrogen-hydrogen bond in the amine compounds.
In particular, during the patterning process, a time delay effect for further process after exposure, a so-called post exposure delay effect, occurs and enlarges the contamination problem concerning the fluorine based photosensitive compound by the amine compound such as ammonia in the atmosphere. Therefore, a recent demand exists for a novel anti-reflective coating material or patterning process to minimize the contamination of the photoresist film due to the post exposure delay after the exposure.
Accordingly, due to such problems in the conventional art, there is a need for an additional anti-reflective coating material which can minimize contamination of the photoresist film caused by amine compounds even when it generates the post exposure delay after the exposure while having no adverse effect to formation of patterns by exposure and development processes. In addition, there is a need for techniques which can further reduce alteration or distortion of the pattern caused by the diffused reflection as the anti-reflective coating material is applied together with the conventional anti-reflective coating typically introduced on the bottom portion of the photoresist. An improved method for forming a pattern by employing such anti-reflective coating material is also needed.